At present, discussion about extension of a luminance dynamic range of a video signal from the known standard dynamic range (SDR) is ongoing in the International Telecommunication Union-Radio (ITU-R) communications sector. The extended dynamic range is called extended image dynamic range television (EIDRTV) or more simply a high dynamic range (HDR). In the recent status of ITU-R, two schemes, Application-1 and Application-2, are expected to be included as signal schemes for HDR video signals in recommendation.
Application-1 is a signal scheme based on Perceptual Quantizer (PQ)-Electro-Optical Transfer Function (EOTF) for the purpose of expressing absolute values of luminance of imaging environments (see Non-Patent Literature 1). Application-2 is a signal scheme of expressing relative luminance levels using a hybrid log-gamma (HLG) curve in which a gamma curve at a luminance level lower than the reference white and a logarithmic curve at a luminance level higher than the reference white are combined (see Non-Patent Literature 2). In Application-1, absolute luminance of a maximum of 10000 cd/m2 can be expressed. On the other hand, in Application-2, relative luminance of a maximum of 12 times the reference white (20 times in a case in which headroom is used) can be expressed.
ITU-R Application-1 is the same scheme as ST2084 formulated by the Society of Motion Picture and Television Engineers (SMPTE) which is a different standardization organization from ITU-R. There are also other signal schemes similar to SMPTE ST2084 (see Non-Patent Literature 3).